U.S. patent number 4,236,516 [Application Number 05/878,267] was granted by the patent office on 1980-12-02 for syringe and disposable container therefor.
Invention is credited to Nils B. Nilson.
United States Patent |
4,236,516 |
Nilson |
December 2, 1980 |
Syringe and disposable container therefor
Abstract
In a syringe comprising a barrel and a plunger reciprocably
mounted therein the end wall of the barrel at the discharge end
thereof is formed by a disposable container removably attached to
the barrel. A flexible wall portion of the container facing the
plunger is moved towards and away from a rigid wall portion of the
container by the reciprocating movement of the plunger in order to
decrease and increase, respectively, the interior volume of the
container.
Inventors: |
Nilson; Nils B. (Mjolby,
SE) |
Family
ID: |
24746395 |
Appl.
No.: |
05/878,267 |
Filed: |
February 16, 1978 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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684020 |
May 7, 1976 |
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Current U.S.
Class: |
604/214; 222/95;
222/107; 222/215; 604/135; 604/222; 604/235 |
Current CPC
Class: |
A61J
1/062 (20130101); A61M 5/282 (20130101); A61M
5/31525 (20130101); A61M 5/31563 (20130101); A61M
5/31591 (20130101); A61M 5/3156 (20130101); A61M
5/31555 (20130101); A61M 5/3158 (20130101); A61M
5/31535 (20130101); A61M 5/3155 (20130101); A61M
5/31561 (20130101); A61M 2205/582 (20130101) |
Current International
Class: |
A61M
5/28 (20060101); A61M 005/24 () |
Field of
Search: |
;128/215,216,218,234,219,232,2F,275-278,DIG.5
;222/95,105,107,215,386.5,389 ;73/425.6 ;141/2,23-25,27,357
;417/550,555R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Truluck; Dalton L.
Attorney, Agent or Firm: Finnegan, Henderson, Farabow,
Garrett & Dunner
Parent Case Text
This is a continuation of application Ser. No. 684,020, filed May
7, 1976, now abandoned.
Claims
What is claimed is:
1. A syringe comprising an elongated barrel having an open
discharge end, a plunger reciprocably mounted in the barrel, a
container, means for removably engaging the container to the
discharge end of the barrel to form the end wall thereof, said
engaging means including a circumferential flange on said
container, said flange having at least a flexible periphery for
being flexed by the end of the barrel when the container is being
engaged as the end wall thereof and for retaining said container as
the end wall of the barrel by the tendency of at least said
flexible periphery of the flange to restore to its unflexed state,
and means on said barrel at said open end for flexing at least said
flexible periphery and permitting restoration of said flange toward
its unflexed state, said container having a substantially rigid
first wall portion at the exterior side of the end wall and having
an inside surface, and a flexible second wall portion at the
interior side of the end wall and introvertible upon the inside
surface of the first wall portion, said plunger having an end
surface facing the container and designed to contact said second
wall portion and to introvert the flexible wall portion upon the
rigid wall portion during reciprocable movement of the plunger,
said end surface being shaped to substantially conform to the shape
of said inside surface of said first wall portion, and a nozzle on
said first wall portion for attaching a hypodermic needle
thereto.
2. A syringe as claimed in claim 1 wherein said flange is flexible
and wherein said barrel includes a cylindrical socket at the
discharge end thereof for receiving said flange and wherein said
socket includes radially inwardly projecting means for receiving
said flange by the flexing of the flange and for retaining said
container in said socket during application of the piston on the
flexible wall portion for introverting the latter upon the inside
surface of the rigid wall portion.
3. A syringe as claimed in claim 2 wherein said flange includes a
peripheral lip projecting from the edge of the flange at the side
thereof which is opposite to said flexible second wall portion of
the container, said lip having a conical outside surface the
largest diameter of which is larger than the inside diameter of
said socket, said lip yielding towards the container when inserted
into the socket to frictionally engage the inner wall surface of
the socket.
4. A syringe as claimed in claim 2 wherein said projecting means
comprises a circumferential rib on the inside wall surface of the
socket.
5. The syringe of claim 4 including means for permitting said end
surface of said plunger to eject said container from said barrel
upon further movement of said plunger toward said discharge end of
said barrel after the introverting of said second wall portion upon
the inside surface of the first wall portion.
6. The syringe of claim 4 wherein said container is prefilled
before attachment to said barrel.
7. A syringe as claimed in claim 1 further comprising valve means
controlling the passage between opposite sides of the plunger in
the barrel to allow free flow of air from one side of the plunger
to the other side thereof when the plunger is being displaced
towards the discharge end of the barrel, and to prevent air flow
between opposite sides of the plunger when it is displaced in the
opposite direction, the interior of the barrel on the side of the
plunger opposite to the discharge end of the barrel being vented to
the atmosphere.
8. A syringe as claimed in claim 7 wherein said valve means
comprises a sealing element on the plunger forming a conical lip
thereon flared from a small end joining the plunger towards the end
of the barrel which is opposite to the discharge end and engaging
the inside wall surface of the barrel, said lip allowing air to
pass between the plunger and the inside wall surface of the barrel
when the plunger is being displaced towards the discharge end, and
being forced to sealing engagement with said inside wall surface of
the barrel when the plunger is being displaced in the opposite
direction in the barrel.
9. A syringe as claimed in claim 7 wherein said syringe functions
to fill said container and wherein said syringe includes
interengaging abutment means on the plunger and the barrel for
limiting the axial displacement of the plunger in the barrel during
filling of said container for automatically filling the container
to a predetermined extent.
10. A syringe as claimed in claim 9 wherein said abutment means on
the plunger comprises several abutments at different axial
positions spaced around the plunger, the barrel and the plunger
being relatively rotatable to place said abutment means on the
barrel in the moving path of any one of said several abutments at
one time.
11. A syringe as claimed in claim 1 further comprising spring means
between the plunger and the barrel biasing the plunger away from
the discharge end of the barrel, and means for selectively
retaining the plunger in a position in which said flexible second
wall portion of the container is introverted by the piston to be
collapsed against the inner surface of said one wall portion of the
container.
12. A syringe as claimed in claim 11 wherein said retaining means
are engaged and disengaged by relative rotation of the barrel and
the plunger.
13. A syringe system comprising a syringe having an elongated
barrel with an open discharge end, a plunger reciprocably mounted
in the barrel, a plurality of disposable containers, means for
removably attaching the containers individually to the discharge
end of the barrel to form the end wall thereof, each said container
having a substantially rigid first wall portion for forming the
exterior side of the end wall and having an inside surface, and a
flexible second wall portion at the interior side of the end wall
and introvertible upon the inside surface of the first wall
portion, said plunger having an end surface facing a container when
attached to the barrel and designed to contact said second wall
portion during the reciprocable movement of the plunger, said end
surface being shaped to substantially conform to the shape of said
inside surface of said first wall portion, anda nozzle on said
first wall portion for attaching a hypodermic needle thereto, means
for removably storing at least a portion of said plurality of
containers and forming a bottom hole for each container for
receiving the nozzle thereof and for closing the open end of the
nozzle and thus the interior of the container to the atmosphere,
said attaching means including flexible flange means on each of the
containers and engagement means on the open end of the barrel, said
engagement means capturing said containers individually by flexing
said flexible flange means, the tendency of the flexible flange
means to restore to its unflexed condition, retaining the container
on the barrel for withdrawing the container from the storing means
with the barrel.
14. The syringe of claim 2, including means for permitting said end
surface of said plunger to eject said container from said barrel
upon further movement of said plunger toward said discharge end of
said barrel after the introverting of said second wall portion upon
the inside surface of the first wall portion.
15. The syringe of claim 2 wherein said container is prefilled
before attachment to said barrel.
16. A container arranged to be attached to a syringe, said
container having a substantially rigid first wall portion, said
first wall portion having an inside surface, a flexible second wall
portion introvertible upon the inside surface of the first wall
portion, and a nozzle on said first wall portion for attaching a
hypodermic needle thereto, said container further comprising a
flange on said first wall portion forming a peripheral lip which
projects from the edge of the flange at the side thereof which is
opposite to said flexible second wall portion of the container,
said lip having a conical outside surface.
17. In a method for operating a syringe comprising an elongated
barrel having an open discharge end, a plunger reciprocably mounted
in the barrel for sealingly engaging the inner surface of the
barrel as the plunger is displaced away from the discharge end, a
container, means for removably attaching the container to the
discharge end of the barrel to form the end wall thereof, said
container having a substantially rigid first wall portion at the
exterior side of the end wall and having an inside surface, and a
flexible second wall portion at the interior side of the end wall
and introvertible upon the inside surface of the first wall
portion, said plunger having an end surface facing the container
and shaped to substantially conform to the shape of said inside
surface of said first wall portion, and a nozzle on said first wall
portion for attaching a hypodermic needle thereto, wherein the
means for removably attaching the container to the open end of the
barrel includes a flexible flange on the containers for permitting
retention of the container as the end wall of the barrel only by
flexing interaction between the flange and the barrel and wherein
the step of drawing the flexible second wall portion from a
collapsed position in which it contacts and substantially conforms
with said first wall portion, in order to draw liquid into said
container through said nozzle, by displacing the plunger in the
barrel away from the container and creating thereby a partial
vacuum in the space of the barrel between the container and the
plunger, by the sealing engagement of the plunger with the
barrel.
18. The method as claimed in claim 17 further comprising the step
of returning said flexible second wall portion towards said
collapsed position by displacing the plunger towards the container,
while venting the space in the barrel between the container and the
plunger to the atmosphere, to bring said end surface of the plunger
to contact said second flexible wall portion and to introvert it
mechanically and positively upon the inside surface of said first
wall portion in order to expel liquid drawn into the container
through said nozzle.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to improvements in syringes for effecting
subcutaneous and intramuscular injections of medicaments and the
like into human beings and animals and for taking blood samples
therefrom.
2. Description of the Prior Art
Most syringes now used in hospitals, offices and health centers are
of the disposable type, that is, they are disposed of or discarded
after one use. These syringes usually comprise two pieces--a barrel
and a plunger or piston mounted for reciprocable movement in the
barrel. Both parts are usually made of plastic material. The barrel
has a nozzle at the discharge end for the attachment of a
hypodermic needle or cannula. On the plunger a sealing ring of
rubber material is provided to act as a seal between the plunger
and the inside surface of the barrel. Either the barrel or the
plunger is provided with a scale by which the volume of liquid
drawn into or dispensed from the barrel may be accurately
determined.
As a disposable product a syringe of this type, although made by
modern mass production methods such as injection molding, is
relatively expensive due to the materials and precision involved in
the manufacture thereof. Considering the enormous number of
disposable syringes used over the world each year, estimated at
several billions, the cost and waste of materials is significant
and can hardly be justified. Any reduction in the manufacturing
cost of a syringe, even if it amounts to only a fraction of a cent,
can provide a large saving. Consequently, great efforts have been
made and still are being made to lower the manufacturing costs of
disposable syringes.
These efforts have not so far resulted in a radical change of the
construction or the method of manufacturing of disposable syringes.
They are still constructed as a two piece article which has to be
thrown away in its entirety after having been used only once.
It has not been suggested so far to limit the disposable aspect to
part of the syringe only; a readily apparent problem in connection
therewith is the difficulty to maintain in a satisfactory manner
the sterility of the syringe if a part thereof is to be used more
than once.
It has been proposed to combine a barrel and a plunger with a
replaceable container positioned at the discharge end of the
barrel, the container being introverted or collapsed upon itself in
use by action of the plunger to eject or administer the medicament
contained in the container. Syringes of this type are disclosed in
U.S. Pat. No. 978,488 to Roesch dated Dec. 13, 1910 and in U.S.
Pat. No. 2,514,575 to Hein dated July 11, 1950. However, in these
prior art syringes the container is a prefilled closed cartridge or
capsule which is positioned in the barrel. The barrel is closed at
the discharge end by a continuation of the barrel or by a separate
end cap or like element. A discharge opening is provided at the
discharge end to communicate with the attached needle or
cannula.
A problem with this type of syringe is the possible contamination
of the reusable elements following discharge of the cartridge or
capsule contents. The expended cartridge or capsule must be
withdrawn from the rear of the barrel or the end cap must be
disconnected to permit cartridge or capsule removal. In either
case, any contact of unexpended medicament with the reusable
elements requires that these elements be cleaned and then
sterilized. Additionally this type of syringe only permits
discharge of the container contents and does not allow the
medicament or the like to be drawn into the container under sterile
conditions. This is a problem also for the injection apparatus
disclosed in U.S. Pat. No. 3,308,818 to Rutkowski dated Mar. 14,
1967 wherein a container is located in a barrel which functions as
a gas expansion chamber, and the container is introverted upon
itself by gas pressure produced in said barrel by an explosive
device.
SUMMARY OF THE INVENTION
The present invention overcomes the foregoing problems and
disadvantages of the prior art by providing a syringe in which only
a small part of the apparatus is discarded after each use, the rest
of the syringe being used repeatedly, and wherein this can be
achieved while maintaining a high degree of sterility and without
contamination of the reusable portion. Furthermore, the syringe of
this invention finds utility either in administering or injecting
medicaments or the like from the disposable container, or in
collecting blood samples or other bodily fluids.
Additional objects and advantages of the invention will be set
forth in part in the description which follows, and in part will be
obvious from the description, or may be learned by practice of the
invention. The objects and advantages of the invention may be
realized and attained by means of the instrumentalities and
combinations particularly pointed out in the appended claims.
To achieve the foregoing objects and in accordance with the purpose
of the invention, as embodied and broadly described herein, the
syringe of this invention comprises a barrel and a plunger or
piston reciprocable therein which are both to be used more than
once, and a disposable discharge end portion providing a container,
which is releasably connected with the barrel to be discarded after
each use of the syringe.
More particularly the syringe according to the invention comprises
an elongated barrel having a discharge end, a plunger reciprocably
mounted in the barrel, a container, means for removably attaching
the container to the discharge end of the barrel to form the end
wall thereof, said container having a substantially rigid first
wall portion at the exterior side of the end wall and having an
inside surface, and a flexible second wall portion at the interior
side of the end wall and introvertible upon the inside surface of
the first wall portion, said plunger having an end surface facing
the container and designed to contact said second wall portion
during its reciprocable movement said end surface shaped to
substantially conform to the shape of said inside surface of said
first wall portion, and a nozzle on said first wall portion for
attaching a hypodermic needle thereto.
The invention also provides a container to be used in a syringe of
this type and a syringe system by which the containers may be
stored under sterile conditions and may easily be attached to the
barrel without contamination of the interior space of the
container, as well as a method in operating the syringe according
to the invention.
The accompanying drawings, which are incorporated in and constitute
part of this specification, illustrate one embodiment of the
invention and, together with the description, serve to explain the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view partly in axial cross-section of the
preferred embodiment of the syringe constructed according to the
teachings of the invention, shown prior to the dispensing
operation;
FIG. 2 is a view similar to FIG. 1 of the complete syringe, shown
during the operation sequence;
FIG. 3 is a plan view partly in cross-section of the preferred
embodiment of a syringe system constructed according to the
teachings of the invention comprising a barrel and a reciprocable
plunger together with a magazine for storing under sterile
conditions a large number of empty containers;
FIG. 4 is a side view, partly in cross-section of the magazine
shown in FIG. 3;
FIG. 5 is a fragmentary side view in cross-section of the syringe
disclosing an embodiment for automatically controlling the amount
of liquid to be drawn into or expelled from the syringe
container;
FIG. 6 is a cross-sectional view of a second embodiment of the
syringe constructed according to the teachings of the invention for
withdrawing blood samples or other liquids;
FIG. 7 is a side view of the syringe shown in FIG. 6 with the
container removed; and
FIG. 8 is a sectional view of the syringe shown in FIG. 6 after a
liquid sample has been extracted.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made in detail to the present preferred
embodiments of the invention, examples of which are illustrated in
the accompanying drawings.
Referring to FIGS. 1 and 3 of the drawings which disclose in detail
the construction of the syringe according to the teachings of the
invention such syringe provides a two-part unit which is
constructed for repeated use and comprises an elongated barrel 10
having a discharge end, and a plunger or piston 11 reciprocably
mounted in the barrel. This barrel can be made as an integral
element entirely of metal or a plastic material and preferably is
made of a transparent plastic material.
The barrel forms a cylindrical cavity 12 which widens at a shoulder
12' into an enlarged cylindrical socket 13 at the discharge end of
the barrel, said socket 13 being defined at is periphery by an
integral wall 14. On the shoulder there is positioned an annular
sealing ring 13'. At the edge of wall 14 there is formed on the
inside surface thereof a circumferential, inwardly-directed rib or
lip 15 preferably with a rounded profile. At the end opposite to
the discharge end the barrel has a circumferential recess 16 having
a concave or rounded shape which provides a finger grip by which
the barrel may be grasped during the operation of the syringe. If
desired, the bottom of the groove may be flattened.
The barrel forms a cylindrical passage 17 extending from the inner
end or bottom 12" of cavity 12 through the finger grip portion 16
and opening at the flat end surface 18 of the barrel. Plunger 11
comprises a cylindrical rod 19 which is received in passage 17 and
is slidable therein. Clearance is provided between plunger 11 and
passage 17 to allow air to pass between cavity 12 and the
surrounding atmosphere.
Rod 19 forms a threaded inner end 20 on which is mounted a plunger
head 21, a threaded bottom hole 22 in the plunger head receiving
the threaded end 20 of the rod. This plunger head also forms a
hemispherical end surface 23 facing the discharge end at socket 13
of the barrel, and a flat base surface 24 facing the bottom 12" of
the barrel. Against the base surface 24 there is applied to the
plunger head a sealing element 25 of a soft rubber material such as
silicone rubber. The sealing element is clamped between a washer
20' and the end surface of the plunger head and forms a conical lip
or sleeve 26 which slopes outwardly and sealingly engages, due to
the inherent elasticity thereof, the inside cylindrical surface of
cavity 12. The sealing element also acts as a valve member during
the expulsion step as later described. At the external end of rod
19 this rod forms a disc 27 integral with the rod for manually
operating the plunger.
A container or cartridge constructed to be removably attached to
the discharge end of the barrel to form the end wall thereof is
generally indicated at 30 and comprises a substantially rigid
hemispherical first wall portion 31 at the exterior side of the end
wall and having an inside surface. Said first wall portion forms an
externally protruding centrally positioned nozzle 32 conically
tapered towards the outer end thereof, for attaching a hypodermic
needle or cannula thereto.
Means for removably attaching the container to the discharge end of
the barrel comprises a circumferential flange 33 on the container
which merges into a conical rim 34, see FIG. 3, protruding
outwardly in the same direction as nozzle 32 at one side of the
flange. Said first wall portion 31 of container 30 may be made of a
suitable plastic material. The container further comprises a
flexible second wall portion 35 at the interior side of said end
wall formed by the container when attached to the barrel. Said
second wall portion is connected to the other side of flange 33
preferably by adhesive, melting or ultra sonic welding. Wall
portion 35 preferably is made of a flexible plastic material. It is
introvertible upon the inside surface of the first wall portion 31
to the collapsed position shown in FIG. 3, and in this position
said second wall portion 35 is seen to be dimensioned and formed so
as to contact the concave inside surface of wall portion 31 of the
empty container, following the curvature of said wall portion. This
is the condition in which the container is delivered.
In the collapsed condition, the interior of the container is
accessible through the passage 32' of nozzle 32 and, therefore, the
requirement of sterility is not met if the nozzle passage is left
uncovered when the container is delivered. This passage has to be
closed under sterile conditions and this is preferably made by
delivering several containers in a magazine as shown in FIGS. 3 and
4.
Referring to FIGS. 3 and 4 there is provided a cylindrical housing
40 having a closed end wall 41 and an end wall 42 centrally
apertured at 42a. A cylindrical stem 43 passing through aperture
42a of end wall 42 and being rotatable and axially displaceable
therein projects at one end thereof from the housing and is
provided with a head 44 for the manipulation of the stem. Several
annular sets of radial conical bottom holes 45 are formed in the
stem at axially spaced levels thereof. These holes are each sized
to receive nozzle 32 of a container 30 of the type described above
and to permit retention of the nozzle by a slight press fit in the
hole.
Thus, a plurality of empty containers are fitted to the stem
arranged in axially spaced annular banks thereon, and in this
position the interior of each container is closed from the
surrounding. Consequently, the containers can be stored in this way
in a sterile condition obtained e.g. by gamma radiation of the
containers when fitted to the stem. The lowermost annular bank of
containers rests against an apertured shoulder 46 formed centrally
on the inside surface of wall 42, the aperture 46a thereof being in
registry with aperture 42a, and in this position the stem may be
rotated to bring each of the containers in the lowermost bank of
containers separately opposite an opening 47 in the cylindrical
side wall of the housing for access by the barrel socket 13.
When the lowermost annular bank of containers 30 has been removed
from the magazine, stem 43 will be lowered so that the next annular
bank of containers will bear on shoulder 46 on the apertured end
wall 42 to support the stem and the containers attached thereto. In
this way each annular bank of containers is brought to the level of
opening 47 by axial displacement of stem 43 and when brought to
this level each of the containers of the lowermost bank of
containers can be removed separately from the magazine through
opening 47.
Referring to FIG. 3 the removal of each container through opening
47 is effected by introducing barrel 10 at the discharge end
thereof into opening 47 and by pushing socket 13 into flange 33 and
rim 34 of the container which has been brought opposite opening 47
to receive the flange and rim in socket 13. When the barrel is
being slid over rim 34 to receive the rim in socket 13 the rim
flexes or gives when sliding against rib or lip 15 and then, after
having slipped over the rib or lip, springs out automatically to
engage at the edge thereof the inner side of the rib or lip. By the
engagement thus obtained between the barrel and the container the
container will be retained by the barrel and will be withdrawn from
stem 43 by withdrawal of the barrel. A hypodermic needle or cannula
48 having a socket 48' may be forcefitted manually to nozzle 32 of
container 30 connected with the barrel and, thus, a complete and
operable syringe has been formed.
If the plunger head 21 is not already contacting the concave
outside surface formed by wall portion 35 collapsed against and
following the curvature of the inside surface of wall portion 31 it
is displaced manually to such position to contact wall portion 35,
the end surface of the plunger head being hemispherical to
substantially conform to the inside surface of wall portion 35 when
collapsed against wall portion 31. When the plunger head is being
moved towards the container at the discharge end of the barrel,
said end being closed off by the container forming an end wall of
the barrel air enclosed in front of the moving plunger will pass
between the plunger head and the cavity wall due to yielding of the
conical lip or sleeve 26 of sealing element 25. The atmosphere
communicates with the interior of the barrel through the clearance
around rod 19 in passage 17.
Cannula 48 is then inserted in a bottle or the like containing a
liquid medicament to be received by the container, or in a blood
vessel in order to take a blood sample therefrom, as the case may
be. As the plunger 11 is retracted the conical lip or sleeve 26 of
sealing element 25 will sealingly engage the inside wall of the
barrel due to the fact that it will be brought to expand towards
that wall by the friction between the lip or sleeve and the wall.
The part of cavity 12 enclosed between the plunger head and the
inner end of the cavity is vented through the clearance formed
around rod 19 in passage 17 so that no pressure builds up behind
the plunger head. Thus, a subpressure (partial vacuum) will be
created in cavity 12 between the plunger head and the end wall
formed at the discharge end of the barrel by container 30 a
leakproof seal being provided between the container and shoulder
12' by sealing ring 13'. No air will be able to pass into this
space from the surrounding since an effective seal will be
maintained also between plunger lip 26 and the inside surface of
the barrel wall when the plunger is retracted from the discharge
end as explained above. By the subpressure thus created wall
portion 35 will be progressively withdrawn from wall portion 31 as
shown in FIG. 2 and the container will be filled with liquid.
In operation, to eject the liquid from the container e.g. for
adminstering the medicament or for transferring the blood sample to
a test tube, as the case may be, the container is emptied by
pressing the plunger head 21 against the filled container. During
this operation needle 48 is inserted in a blood vessel or under the
skin of a human being or an animal for administering the
medicament, or alternatively in a test tube or other receiver to
which the blood sample shall be transferred for treatment or test
operations. The flexible wall portion 35 will be introverted
mechanically by the hemispherical end surface 23 of plunger head 21
and will be collapsed against the inside surface of wall portion
31. No overpressure is allowed to build up in front of the plunger
head due to the valve action provided by the lip or sleeve 26 of
sealing element 25 as described above. This is one of the important
features of the syringe system according to the invention. If air
under pressure trapped between the container and the plunger head
were allowed to pass into the container through a perforation in a
defective flexible wall portion 35 the air could arrive in a blood
vessel which could be dangerous to the patient and even mortally,
or build up of compressed air in front of the plunger head could
eject the container from socket 13 of the barrel. If liquid leaks
into the cavity 12 of barrel 10 from a defective container it could
be contaminated by contacting the barrel and the plunger. Such
contaminated liquid will pass to the back side of the plunger head
at lip 26 where the flow resistance is lower than that in the
cannula, and thus will not be administered from the syringe. This
is a further safety feature of the syringe according to the
teachings of the invention.
When the liquid in the container has been expelled therefrom, the
emptied container can be ejected from the barrel by means of the
plunger. An increased force is exerted manually on the flexible
wall portion 35 which contacts wall portion 31 when the container
has been emptied, and under the force thus exerted on the emptied
container rim 34 is brought to yield and to disengage rib or lip
15. The container is thrown away together with the cannula and a
fresh container is attached to the barrel in the manner described.
Thus it will be seen that only a small part of the complete syringe
is provided as a disposable product to be thrown away after each
use. This will considerably reduce the cost for each operation in
relation to the common practice to throw away from each injection
the entire syringe, thanks to the saving of material which also
means that less waste has to be disposed of.
There may be provided on barrel 10 or on rod 19 a graduation or
scale which is read against an index on the rod and the barrel,
respectively, for reading the volume of liquid drawn into container
30. Since the operative connection between wall portion 35 of
container 30 and the plunger or piston head 21 during the suction
stroke of the syringe is provided by the subpressure created in
front of the plunger between the plunger head and the container,
the increase of the interior volume of the collapsed container when
wall portion 35 is moved away from wall portion 31 will be the same
volume as that displaced by plunger head 21 in the cylindrical
cavity 12. This means that the graduation or scale will be
linear.
It is possible to have containers of different size for
co-operation with one and the same barrel so that a number of
standard volumes can be chosen by choosing a container of the
desired volume, although different sized barrels may be used for
containers of different size. Other volumes than standard volumes
may be determined by means of the graduation and the index against
which such graduation is read.
FIG. 5 discloses an arrangement by which a container 30 can be
filled with liquid to a predetermined extent without reading a
graduation. In rod 19 there are provided four axially extending
grooves 49a, 49b, 49c and 49d which are spaced apart ninety degrees
about the axis of rod 19. These grooves are of different length and
they have all the end adjacent disc 27 in a common transverse plane
of the rod. A detent formed by a ball 50 is biased by a pressure
spring 51 received by a cavity 51' formed in the barrel, the ball
thus being pressed against rod 19. This rod may be rotated in
passage 17 to bring one of the grooves into register with the ball.
Such rotation takes place against the resistance offered by ball 50
when it is forced out of the groove in which it is received at the
time, against the bias provided by spring 51. In FIG. 5 the ball is
received by groove 49a. When the plunger is displaced axially the
ball rides in the groove and offers increased resistance to
movement beyond the ends of the groove to indicate the length of
the stroke defined by the groove cooperating with the ball. When
the plunger is being displaced for sucking liquid into the
container attached to the barrel, the ends of the axial distance
represented by a groove such as groove 49a will be felt as a
pressure point at each end of the axial distance represented by the
groove. The length of each groove may be adjusted to correspond to
a predetermined volume of liquid in the container. If a greater
volume is desired rod 19 may be rotated in order to bring the
proper groove into register with ball 50. It is possible to adjust
the volume by means of a graduation 52 provided on rod 19, end wall
18 of the barrel forming an index for reading such graduation, in
case it is wanted to fill the container to an extent which does not
correspond to one of the standard volumes represented by the
grooves. The longest groove 49d should preferably correspond to
complete filling of the container.
In FIG. 6 to 8 there is disclosed an embodiment of the invention
which has been developed preferably to assist in taking blood
samples from a human being or an animal. In this case there is
provided on barrel 10' a socket or sleeve 53 having an open end.
The barrel slides telescopically in and is received by this sleeve
which at the other closed end is connected to the outer end of rod
19. Between the end surface 18' of the barrel and the bottom of
sleeve 53 there is arranged a helical compressed spring 54 biasing
the barrel and the sleeve to extend the barrel from the open end of
the sleeve as disclosed in FIG. 8. As in the previous embodiment
there is provided a socket 13 receiving flange 33 and rim 34 of a
container 30 but in this case there is no rib such as rib 15 in
FIGS. 1 to 3 provided on the inside surface of the side wall 14 of
socket 13. Since the syringe in this embodiment of the invention is
adapted for sucking liquid into the container when a blood sample
is being taken but not for expelling the blood from the container
when connected with the barrel the frictional engagement between
rim 34 and the inside of wall 14 is sufficient to maintain the
container on the barrel the more so as the subpressure created
between the container and the plunger head when the plunger is
withdrawn forces the container to be pressed against sealing ring
13' on shoulder 12'. Socket 13 is extended at 14' to form together
with the rest of barrel 10' an annular groove 55 for receiving
sleeve 53 as shown in FIG. 6, which can be brought to this position
by displacing plunger head 21 towards the discharge end of barrel
10' by movement of the barrel within sleeve 53 against the action
of spring 54 thereby compressing the spring. For arresting sleeve
53 in this position there is provided in the sleeve a notch 56 of
the form disclosed in FIG. 7 and there is provided on socket
extension 14' a pin 57 extending radially inwardly which may be
brought into engagement with notch 56 by introducing the pin into
the notch when sleeve 53 is pressed against the discharge end of
barrel 10' and then rotating the sleeve so that the condition
disclosed in FIG. 7 will be obtained.
In this case there is provided in nozzle 32 a stopper 58 of a soft
rubber material which is designed to be penetrated by a
double-ended cannula 59 manually fitted to the nozzle by an
attachment 60. This cannula is inserted into the blood vessel and
then sleeve 53 is rotated in order to disengage it from pin 57.
When the sleeve is released it will be displaced in relation to
barrel 10' by means of spring 54, the plunger thereby being
retracted or withdrawn in barrel 10' in order to draw the blood
into container 30 in the manner described with reference to the
embodiment disclosed in FIGS. 1 to 5, the movement of the plunger
being accomplished automatically by means of spring 54, not
manually as in FIGS. 1 to 5.
Once the container has been filled with blood the cannula may be
removed from the nozzle. Stopper 58 will close automatically the
passage through the nozzle. The container may be removed from the
barrel manually in order to be transferred to a laboratory or to a
storage freezer for future use.
The double-ended cannula 59 may be provided with well-known valve
means (not shown) in order to close off the passage through the
cannula when it is withdrawn from the container. Such valve means
are disclosed e.g. in U.S. Pat. Nos. 3,469,572 to Nehring and
3,585,984 to Buchanan. Thus, several blood samples may be taken
through one and the same cannula with only one penetration of the
blood vessel.
It will be apparent to those skilled in the art that various
modifications and variations could be made in the syringe of the
invention and in the container forming part thereof without
departing from the scope or spirit of the invention.
* * * * *